Push-button key assembly

ABSTRACT

Push-button key structure, for use in adjustable radio tuning apparatus. The parts of the key structure are constructed and arranged to enable mechanized assembly of the push-button keys. Each key assembly comprises a pair of elongate slide members one of which carries an adjustable and lockable cam engageable with a treadle bar the angular position of which determines the tuning of associated radio apparatus. The keys are so designed that they may be completely assembled by interlocking engagement of the component parts thereof, using automatic machinery capable of only rectilinear movements. Provision is made for forcible &#39;&#39;&#39;&#39;sizing&#39;&#39;&#39;&#39; of parts of the key to maintain them in proper position and establish the tolerances required to ensure proper operation of the cam.

United States Patent Thompson [54] PUSH-BUTTON KEY ASSEMBLY Alvin E.Thompson, North Wales, Pa.

[22] Filed: Oct. 19, 1970 [21] Appl. No.: 81,897

[72] inventor:

[52] US. Cl ..74/l0.33, 334/7 [51] Int. Cl ..F16h 35/18 [58] Field ofSearch....74/l0.33, 10.31, 10.29, 10.27,

[56] References Cited UNITED STATES PATENTS 3,086,401 4/1963 Horton..74/l0.33 3,195,359 7/1965 Clark ..74/10.33

Primary Examiner-Milton Kaufman Attorney-Robert D. Sanborn, William E.Denk, Herbert Epstein and Harry W. Hargis, 111

[5 7] ABSTRACT Push-button key structure, for use in adjustable radiotuning apparatus. The parts of the key structure are constructed andarranged to enable mechanized assembly of the push-button keys. Each keyassembly comprises a pair of elongate slide members one of which carriesan adjustable and lockable cam engageable with a treadle bar the angularposition of which determines the tuning of associated radio apparatus.The keys are so designed that they may be completely assembled byinterlocking engagement of the component parts thereof, using automaticmachinery capable of only rectilinear movements. Provision is made forforcible sizing of parts of the key to maintain them in proper positionand establish the tolerances required to ensure proper operation of thecam.

5 Claims, 6 Drawing Figures PUSH-BUTTON KEY ASSEMBLY BACKGROUND OF THEINVENTION This invention is particularly useful in push-buttonsettingofa push-button key is effected by withdrawing theextension slidemember to free the cam, tuning the set to the desired station, andsubsequent inward movement of the'extension slide member, with respectto the main slide member, which brings the cam into engagement with thetreadle bar and locks it in position. Thereafter depression of that keytunes the receiver to the selected station. Since locking of the cam isbrought about by inward sliding movement of the extension slide member,such apparatus has frequently been designated as being of thepush-to-lock type.

Push-button keys of this known kind have proven difficult tomanufacture, and the large amount of handwork which has hitherto beenrequired, during assembly of the component parts which comprise the key,has substantially increased the cost of the apparatus. When attemptswere made to mechanize the assembly process, problems were encounteredbecause of the complex, frequently twisting, motions which had to beapplied to the parts to bring the same to interlocking position.Problems have also arisen from the fact that it has been difficult tomanufacture the key assemblies with such precision that the clampingpressure applied to the cam is sufficient to insure consistent andreliable operation of the cam in driving the key bar, and yet is socontrolled that the cam is reliably unclamped when the finger-operatedextension slide is returned to its withdrawn position with respect tothe main slide member.

SUMMARY AND OBJECTIVES OF THE INVENTION It is the general objective ofmy invention virtually to eliminate the need for twisting motions, andconsequent handwork, in assembling such keys, and to reducemanufacturing costs, by providing key parts which are so constructed asto enable automatic assembly by relatively simple machines capable ofonly rectilinear motions. To this end I provide a main slide memberhaving an aperture through which a T-bar or lug, struck from the metalof the extension slide member, can be inserted and in which apparatusonly rectilinear movement is required for insertion and for relativemovement of the slide members, to a position in which they interlock. Myapparatus is featured by the use of a small lateral projection which isdeformable after assembly, being movable a distance sufficient toprevent the T-bar from fully confronting the mentioned aperture. TheT-bar, in cooperation with this projection, holds the slide members inassembled relament of the frequencydetermining' device. Thus;

tion. Deformation and locking of the projection is readily accomplishedby a simple rectilinear motion.

It is a particular objective of this invention to provide a novel methodfor sizing parts of the assembled key, in a manner which does not relyon sensing the stacked thicknesses of various parts, as has been done inthe past. Obviously variations in thickness can interfere with propersizing.

Another feature which facilitatesmachine assembly of the keys involves anovel shape and function of the leaf spring which preloads the usual camclamping lever toward the non-clamping condition.

' BRIEF DESCRIPTION or THE DRAWINGS FIG. 1 is an elevational view on anenlarged scale, showing a push-button slide assembly constructed inaccordance with my invention; 7

FIG. 2 is an elevational view showing portions of the assembly shown inFIG. 1 full size and from the underside;

applied to FIG. 1, and illustrating the key member with the extensionslide member withdrawn to a position at which the cam is free foradjustment;

FIG. 4 is a fragmentary sectional view similar to FIG.

3, and illustrating the extension slide member in its forward positionin which the cam is locked in position on the main slide member;

FIG. 5 is a view similar to FIGS. 1 and 2, and illustrating, on a largerscale, upper and lower fixtures which are used to size the assembly andinsureproper release and clamping of the cam; and

FIG. 6 is a fragmentary perspective illustration of a portion of theupper sizing fixture.

DESCRIPTION OF THE PREFERRED EMBODIMENT First with general reference tothe drawing, there is illustrated a push-button or key assembly whichcomprises a main slide member 10 and a finger-operated extension slidemember 11, said slide members being relatively extensible to permitadjustments, and also being slidable as a unit to effect a tuningoperation. A cam 12 is carried by the main slide member 10, beingmounted on the latter through the agency of a cylindrical projection 13which, conveniently, is raised from the metal of the main slide member10 and provides a journal about which the cam 12 may pivot. As is wellknown in this art, depression of the key assembly as a unit, by pressureexerted against the finger button shown at 14 in FIG. 1, effects tuningof the receiver by positioning a pair of rods l5l5 which are coupled toform a treadle bar assembly, in accordance with known practice. Thetreadle bar is associated with frequency determining means which neednot be illustrated herein. Setting of the push-button is brought aboutby withdrawing the extension slide member 11, with respect to the mainslide member 10, as is explained below.

The mechanism is designed to permit placement of the parts of the keyassembly on a holding fixture and subsequent assembly of the parts bymachinery (not shown) which need be capable of only lateral and verticalmotions. With the main slide member 10 held on a suitable fixture, forexample the lower fixture shown FIG. 3 is a sectional view, taken alongthe line 3-3 A fragmentarily at 16 in FIG. 5, a bar or lug 17 whichextends laterally from the body of the extension slide member 1 1, isfitted through a loading notch 18 formed in the main slide and which isof a size to receive the lug 17, including its laterally extendingT-shaped projections 19. This arrangement is clear from FIG. 2, whichshows the assembly of FIG. 1 from the underside. By moving the extensionslide member 11 rectilinearly along and toward the right-hand end of themain slide member 10, as the latter is viewed in the drawings, the T-baror lug 17, 19 moves into a position in which it occupies a narrowerrestraining portion 18a of loading notch 18. In this position, which isillustrated in FIG. 2, the two slide members are held in assembledrelation. A pair of flange projections 20-20, formed as parts ofextension slide member 11, cooperate with edge portions 21 of the mainslide member 10, to prevent lateral cocking movements of one slidemember with respect to the other.

The apparatus is featured by the use of a small lateral projection 22which is readily deformable after assembly of the slide members to aposition (shown in dotted lines at 22a in FIG. 1, and in full lines inFIG. 2), in which position it is in interference relation with one ofthe projections 20 when the extension slide member is withdrawn to theleft with respect to the main slide member 10. When the projection 22has been deformed, which may readily be accomplished by the use ofautomatic machinery, it limits withdrawal movement of the extensionslide member 11 to a distance such that the Tbar extensions 19 do notfully confront the loading notch 18 (FIG. 2). In summary as to thisfeature, the T-bar, in cooperation with projections 20 and 22, holds theslide members in assembled relation without the need for studs orrivets.

As is common in this art, and as has been briefly mentioned above, cam12 is freed for pivotal movement to a new station-selecting position bywithdrawing the extension slide member to the left, with respect to themain slide member 10, to a position in which the cam is unclamped. Whilesuch clamping and unclamping movements of the cam are not broadly new,the apparatus which effects the same will now be described briefly, inorder that certain new features thereof may be understood.

A cam clamping lever of generally known type, is shown at 23. Theright-hand end of this lever is provided with bifurcations 24-24 whichfit beneath and bear against T-shaped extensions 25 formed as a part ofa T-bar or lug 26 (see particularly FIGS. 1-3) which extends from themain slide member 10. The construction and relative arrangement of theextensions 25 and clamping lever 23, and the way in which these partsare sized to provide proper operation of the cam, is explained later inthis description.

The left-hand end of clamping lever 23 is provided with a curved portionwhich is shaped to cooperate with an inclined cam surface 27 formed as apart of the first mentioned T-lug 17. As will be clear from a comparisonof FIGS. 3 and 4, when the extension slide 11 is in the withdrawnposition (FIG. 3), cam surface 27 is disengaged from the curved endsurface of locking lever 23, with result that the lever pivotsdownwardly, to the position shown in F IG. 3, under the urging of agenerally flat leaf spring S one end of which makes contact with theunderside of the right-hand end of the clamping lever 23, and theopposite end of which reacts against a locating stud 28, formed as apart of main slide member 10, and against a rivet 29 which stakes thespring to the main slide lever. For the sake of clarity in illustratingother parts, the left end of spring S is shown broken away in FIGS. 3and 5.

When the clamping lever occupies the position shown in FIG. 3, its camcontacting projections 30 are withdrawn from the upper surface of thepivotable cam 12, leaving the latter free to rotate upon its journal 13.In accordance with usual practice, manual tuning of an associatedreceiver to a desired station, and subsequent reclamping of the cam 12,conditions the receiver to receive the selected station in response tosubsequent actuations of that key. It should be appreciated that thespring S not only serves to preload the cam clamping lever 23 toward thenon-clamping position, but also is effective to retain the cam 12properly assembled with respect to the journal projection 13 since itprevents any substantial movement of the cam away from the supportingsurface of main slide member 10.

It is important to note that assembly of the cam over the projection 13,and mounting of the spring S in position beneath the bifurcated ends 24of lever 23, which ends underlie extensions 25 of T-bar 26, may all bebrought about without the complex and frequently twisting motions whichhad to be applied to the lever, spring, and cam parts of the kind usedheretofore. In prior constructions the spring body frequently wasapertured intermediate its ends to accommodate the T- projections whichcooperate with the lever in clamping the cam. This earlier type ofconstruction required that the spring be turned with respect to theT-bar and twisted back to proper longitudinal position, after which therearward part of the spring was snap-engaged I with a cam-holding stud.These motions cannot readily be carried out by automatic machinery.

The cam is reclamped, during adjustment thereof, by moving the extensionslide member 11 toward the right with respect to the main slide member10 into position in which its cam surface 27 forces the left-hand endportion of the locking lever upwardly to the position shown in FIG. 4.In this elevated position, in which the locking lever is flexed veryslightly, the studs 30 which are carried by the bifurcated ends 24 ofthe locking lever bear forceably against the upper surface of cam 12,forcing it against member 10 and preventing any pivoting movement of thecam with respect to the main slide member.

The manner in which the parts are configured to insure proper clampingpressure and the method of sizing certain parts in the achievement ofconsistent and reliable operation of the cam will now be described.First making reference to FIGS. 1 and 3, it will be observed that thebifurcations which form the right-hand end of the clamping lever 23 aredepressed or coined in a manner to provide shallow indentations 31extending across each of the bifurcations 24. These indentationsunderlie the cross-head which forms the lateral projections 25 of theT-bar 26. The right-hand portion of each indentation 31, when viewed inelevation, is recessed to a lesser degree than the left-hand portion.This results in inclining the surface of each indentation upwardlytoward the cam-clamping end of lever 23. In accordance with my inventionknife-edge interengagement between the lever and the T-projections 25 isinsured by the mentioned inclination of the coined or indented area andby so shaping the lug 26 that the lower edge which lies most closelyadjacent to the clamping end of lever 23 is oppositely inclined. Theresult is knife-edge contact of the projections 25 along the line shownat 32 where the projections bear against the upwardly inclined surface31 of lever 23. This feature insures that the actual contact between thelever and the T-projections 25 occurs in a predetermined region whichmaximizes the force developed by the clamping moment arm measured fromthe knife edge to the center of the clamping projections 30.

Particularly characteristic of my invention is the way in which theT-bar 25-26 is sized downwardly to a position in which the parts areretained in proper relation and the tolerances are established which arerequired to insure proper operation of the cam. In accordance with thisconcept, a small aperture 33 (see FIGS. 3 and 5) is provided in the mainslide member beneath the cam 12 and through which aperture may extend areciprocable plunger associated with fixturing apparatus used during thesizing. A lower fixture part, for

example part 16 to which reference has already been i made, is used tosupport the key assembly, while an upper horizontally and verticallytranslatable fixture element, shown fragmentarily at 34, carries a ram35 adapted to contact and move the T-lug 26. When the of cam 12. Thisholds the cam in the elevated position shown in phantom lines in FIG. 5,since the extension slide member 11 has been withdrawn from beneath theleft end of locking lever 23. M

The illustrated fixturing apparatus is utilized in the practice of mynew method of sizing the key assembly, which method produces assemblieswhich are more uniform in clamping pressure. In previous push-to-lockmechanisms there was a tolerance build-up due to the thicknesses of thecam, lever and slide parts, and resultant differences in the amount ofdeformation which occurred in the clamping lever when it was forced intoits upper clamping position. In serial production of the keys, thesedifficulties resulted in undesirable variations in clamping pressure andconsequent interference with subsequent reliable operation of the cam.All of these variables are compensated for by accomplishing sizing bybending the main T-projection 26 rearward (toward the right) anddownward, until a desired predictable tolerance is established, assensed by displacement of the plunger 36 which operates a switch device(not shown) adapted to control the supply of power to upper fixture 34and ram 35. In this way precise sizing is accomplished which does notrely upon sensing the stacked thicknesses of the various parts.

When the apparatus is ready for sizing, the lug or projection 26 extendsgenerally vertically, as is shown in broken lines at 26a in FIG. 5. As afirst step in the sizing process relative translational movement betweenthe lower fixture portion 16 and the upper fixture element 34 iseffected, most conveniently by translating the upper element 34 in thedirection indicated by the arrow A. An angled surface 35a of ram 35(FIG. 6)

makes contact with upper portion of the T-slug 26 forcing it to theright, a distance equal to about 0.020 inch measured from the originalvertical position. This motion angles the T-lug to produce theabove-mentioned knife-edge contact at 32 and a desired predictableclamping moment arm. The ram 35 is then translated downwardly, as shownby the arrow B, bending or deforming the T-lug 26 to a predetermineddegree as sensed by a switch associated with the plunger 36. Desirably,the ram 35 should be capable of about 0.030 inch vertical displacement.Using key parts of the general dimensions which have become accepted inthe industry, the ram was translated downwardly about 0.016 to 0.019inch, that is until it occupies the position shown in full lines in FIG.5.

The cam, spring and slide parts are so dimensioned that, prior to thesizing operation, the plunger 36 holds the cam elevated above thesurface of main slide 10 a distance equal to about 0.020 inch.Satisfactory and reliable clamping pressure can be insured by forcingthe cam 12 downwardly to the position shown in full lines, that is,until it is spaced above the slide member 10 a distance between about0.001 and 0.006 inch. When the plunger 36 senses that such position hasbeen reached it cuts off power to the ram, with the result that thevertical distance between the knife edge 32 and the cam-contactingsurface of main slide 10 can be held constant through series assembly ofmany push-button keys. This insures that, when the extension slidemember 11 is moved to the right, and the cam clamping lever 23 is forcedupwardly, the distance moved by the cam clamping projections 30 isconstant and a relatively uniform locking force is applied in each camassembly manufactured.

Iclaim:

l. A push-button key for use in presettable push-button tuners,including: an elongate main slide member carrying a pivotable cam andprovided with a guide slot extending in the direction of the length ofsaid slide member and which slot has adjacent one end thereof a widerportion which extends laterally of the slide member; a finger-operableextension slide member having a generally T-shaped projection movablerectilinearly through the laterally extending portion of said guide slotand thereafter movable rectilinearly toward a narrower portion of saidslot spaced from said wider portion to a position in which said slidemembers are in interlocking engagement; and stop means carried by saidmain slide member in a position in which it prevents return movement ofsaid T-shaped projection through said wider portion and therebymaintains said slide members in interlocking engagement.

2. A construction in accordance with claim 1, and further including anelongate locking lever, one end of which is bifurcated to react againsta second generally T-shaped projection extending from the main slidemember, the bifurcations of said one end being disposed beneath the headportion of the T-shaped projection with said bifurcations astride theleg portion of said projection, the other end of said lever beingdisplaceable, in response to movement of said extension slide memberwith respect to said main slide member, so that the bifurcated end bearsagainst and locks the cam against pivotal movement with respect to themain slide member.

3. A construction in accordance with claim 2, and further including leafspring means one end of which is secured to said main slide member andthe other end of which terminates beneath and is engaged with thebifurcated end of said locking lever, the construction and arrangementof the leaf spring means being such that it retains said cam inassembled relation with respect to said main slide member and exerts aforce biasing the bifurcated end of said clamping lever toward aposition in which the cam is free for pivotal movement.

4. In a push-button key assembly of the kind including main andauxiliary overlapping slide members each of which has a generallyT-shaped lug extending laterally therefrom, one of said T-lugs servingto retain said slide members in assembly and the other of said T- lugsproviding a fulcrum about which pivots a lever adapted to lock a camcarried by the main slide member, the improvements which comprise:provision of bifurcations on one end of the locking lever, saidbifurcations having indented portions underlying the lateral projectionsof said other T-lug, the surface of said indented portions being soangled upwardly toward said end of said lever, and said other T-lugbeing so inclined with respect to said indented portions, that the T-lugmakes knife-edge contact with said indented portions, said locking leverbeing pivotable about the knife-edge, in response to relative slidingmovement between said main and auxiliary slide members, to clamp the camagainst the main slide member.

5. A push-button key assembly of the kind including main and auxiliaryoverlapping slide members each of which has a generally T-shapecl lugextending laterally therefrom, one of said T-lugs serving to retain saidslide members in assembly and the other of said T-lugs providing afulcrum about which pivots a lever adapted to lock a cam carried by themain slide member, and in which assembly:

the fulcrum-providing T-lug is disposed in a midregion of said mainslide member; the cam is disposed toward one end thereof; the lockinglever extends from the lasbmentioned T- lug toward the opposite end ofsaid main slide member, into position to be actuated by movement of saidauxiliary slide member; and there is included a leaf spring secured tosaid main slide member between the cam and said one end, said leafspring having a portion extending toward said other end across said cam,to secure the same, and into a position in which it terminates beneathand bears resiliently against the end of said locking lever.

1. A push-button key for use in presettable push-button tuners,including: an elongate main slide member carrying a pivotable cam andprovided with a guide slot extending in the direction of the length ofsaid slide member and which slot has adjAcent one end thereof a widerportion which extends laterally of the slide member; a finger-operableextension slide member having a generally T-shaped projection movablerectilinearly through the laterally extending portion of said guide slotand thereafter movable rectilinearly toward a narrower portion of saidslot spaced from said wider portion to a position in which said slidemembers are in interlocking engagement; and stop means carried by saidmain slide member in a position in which it prevents return movement ofsaid T-shaped projection through said wider portion and therebymaintains said slide members in interlocking engagement.
 2. Aconstruction in accordance with claim 1, and further including anelongate locking lever, one end of which is bifurcated to react againsta second generally T-shaped projection extending from the main slidemember, the bifurcations of said one end being disposed beneath the headportion of the T-shaped projection with said bifurcations astride theleg portion of said projection, the other end of said lever beingdisplaceable, in response to movement of said extension slide memberwith respect to said main slide member, so that the bifurcated end bearsagainst and locks the cam against pivotal movement with respect to themain slide member.
 3. A construction in accordance with claim 2, andfurther including leaf spring means one end of which is secured to saidmain slide member and the other end of which terminates beneath and isengaged with the bifurcated end of said locking lever, the constructionand arrangement of the leaf spring means being such that it retains saidcam in assembled relation with respect to said main slide member andexerts a force biasing the bifurcated end of said clamping lever towarda position in which the cam is free for pivotal movement.
 4. In apush-button key assembly of the kind including main and auxiliaryoverlapping slide members each of which has a generally T-shaped lugextending laterally therefrom, one of said T-lugs serving to retain saidslide members in assembly and the other of said T-lugs providing afulcrum about which pivots a lever adapted to lock a cam carried by themain slide member, the improvements which comprise: provision ofbifurcations on one end of the locking lever, said bifurcations havingindented portions underlying the lateral projections of said otherT-lug, the surface of said indented portions being so angled upwardlytoward said end of said lever, and said other T-lug being so inclinedwith respect to said indented portions, that the T-lug makes knife-edgecontact with said indented portions, said locking lever being pivotableabout the knife-edge, in response to relative sliding movement betweensaid main and auxiliary slide members, to clamp the cam against the mainslide member.
 5. A push-button key assembly of the kind including mainand auxiliary overlapping slide members each of which has a generallyT-shaped lug extending laterally therefrom, one of said T-lugs servingto retain said slide members in assembly and the other of said T-lugsproviding a fulcrum about which pivots a lever adapted to lock a camcarried by the main slide member, and in which assembly: thefulcrum-providing T-lug is disposed in a midregion of said main slidemember; the cam is disposed toward one end thereof; the locking leverextends from the last-mentioned T-lug toward the opposite end of saidmain slide member, into position to be actuated by movement of saidauxiliary slide member; and there is included a leaf spring secured tosaid main slide member between the cam and said one end, said leafspring having a portion extending toward said other end across said cam,to secure the same, and into a position in which it terminates beneathand bears resiliently against the end of said locking lever.